1. Field of the Invention
The present invention relates generally to a heat exchanger for an automotive vehicle. More particularly, the present invention relates to a heat exchanger of the plate-fin type wherein each of the plates includes a plurality of bead configurations having different heights.
2. Disclosure Information
Plate-fin heat exchangers are well known in the art. In these types of heat exchangers, a plurality of elongate plates are joined together, such as through a lamination process to define a plurality of passageways for movement of a fluid therethrough. Each of the passageways is formed by the inwardly facing surfaces of a pair of joined plates. The interior surfaces of the joined plates generally define a central fluid conducting section. The passageways are interconnected so that a fluid may flow through the plurality of joined plates forming the heat exchanger. As is also known in the art, conductive fin strips are located between outwardly facing surfaces of the pairs of joined plates. Heat exchangers of this type have particular utility as evaporators for air conditioning systems in motor vehicles.
Various plate designs have been proposed for improving the heat transfer coefficient of the heat exchanger. The heat transfer coefficient can be improved by establishing a multiplicity of pathways for the fluid to flow through so that a greater turbulence and a greater mixing of a fluid to be cooled is obtained. One such proposed plate design is shown in U.S. Pat. No. 4,600,053, assigned to the assignee of the present invention. The plate of the '053 patent includes a plurality of beads formed on each of the pair of plates forming one of the passageways of the fluid in the heat exchanger. The laminated plates include two distinct varieties of beads. A first variety of the beads extends above the surface of the plate and terminates in a flat upper surface. The second variety of beads extends above the surface of the laminated plate and terminates in a curved upper surface. The first and second variety of beads are arranged so that when a pair of the plates are laminated together, the first variety of beads on one of the plates is in bonding contact with the second variety of beads on the other of the pair of plates. In this manner, the heat exchanger has a plurality of flow paths established for the fluid in each of the passageways. However, in assembling a pair of plates to be joined, alignment of the plates could be difficult due to slippage between the plates at the points of contact between the two variety of beads. Furthermore, by establishing bead-to-bead contact, less surface area is available on the outwardly facing side of the plate to contact the fins between the adjacent pairs of plates, resulting in less heat transfer capabilities.